Treatment chair

ABSTRACT

Chair for medical or dental treatments, having the back divided into a plurality of adjustable sections with means for maintaining a spacing between the sections and guides for controlling the motion of same, the length of the back being adjustable.

lJnited States Patent Primary Examiner Francis K. Zugel Atlorney- Young & Thompson ABSTRACT: Chair for medical or dental treatments, having the back divided into a plurality of adjustable sections with means for maintaining a spacing between the sections and guides for controlling the motion of same, the length of the back being adjustablev [72] Inventor Harald Holstad 476,922 Bragerness Torv 2a, 3000 Drammen, 477,197 Norway 1,304,821 [21] Appl. No. 822,350 1,548,334 [22] Filed May 5, 1969 2,884,047 [45] Patented Dec. 7,1971 2,933,736 [32] Priority May 14, 1968 2,949,152 [33] Norway 3,330,595 [31] 1878/68 3,462,193 3,477,761

[54] TREATMENT CHAIR 228 386 2 Claims, 6 Drawing Figs. 8 34 [52] US. Cl 297/353,

[51] lnt.Cl A47c l/l0 [50] Field of Search 297/353,

[56] References Cited UNITED STATES PATENTS 358,266 2/1887 Harvey 297/410 PATENTEU DEC 7197;

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TREATMENT CHAIR The present invention relates to a treatment chair, e.g., operation chairs for doctors and dentists.

The most widely used type of treatment chair at the present time, e.g., a dentist chair, has a central post which supports the seat of the chair and is formed as a lifting and lowering means for adjustment of the height of the chair. A further, but not so widely used chair, has the seat portion mounted on an arm which projects from a laterally situated post. As previously stated, the known chairs permit adjustment of height and also adjustment of the angle of the back and the position of the head support. The known types of chairs are only partially satisfactory, however. In order to elucidate this further a summary of the ideal characteristics which should be required of a dentist chair is first set forth.

The treatment chair must be formed so as to fit the anatomy of the patient, and so as to take all varieties of anatomy into consideration. It should be only the patients own anatomy which can possibly form an obstacle to treatment in any position, i.e., that the chair, as such does not constitute any such obstacle.

It should be possible to place the patient in any desirable position for treatment. That is to say it must be possible to place the patient at a height and angle adapted to the method of operation. With regard to the method of operation, a distinction is made between the standing method and the sitting method which last method is becoming ever more widely preferred.

The treatment or operational area should be in the same relation to the instruments and equipment at all times and during all alterations in the position of the chair.

With existing chairs only limited consideration is taken to the variations in anatomy of the different patients. In the question of fitting the chair to the anatomy of the patient, it is the length of spine and the relation of the head to the spine which is of primary importance. Only very limited consideration is taken to this factor in the known chairs, since the chair backs, possibly with appurtenant head supports, do not permit bending to various shoulder heights and thereby obstruct the dentist from approaching sufficiently close to the patient in all operational positions.

The variations in anatomy of the patients may be analyzed. There are short patients and tall patients, obese patients and thin patients and there are also anatomical variations with regard to the position of the head in relation to the line of shoulder and plane of the spine. When constructing a treatment chair it is thus necessary to take into consideration the variations in distance from the seat to the head support, the variations in distance from the shoulder line to the head support and the sagital variations in distance from the line of the spine plane to the head support. In order to achieve the desired anatomical fit of the chair, following adjustments must be possible; it must be possible continuously to adjust the back as to length, there must be a pivotal point or breaking point for the head support, and the locking means here must not project from the rear of the chair. Further the distance from shoulder line to head support must be adjustable. The object of the invention is to satisfy the above requirements and, according to the invention, there is provided a treatment chair which is characterized in that the chair back, for adjustment of the length thereof, is divided into a plurality of relatively displaceable sections.

A preferred embodiment example is characterized by guide mechanisms for continuous adjustment of the spacing between the separate sections.

A suitable construction in accordance with the invention is thus characterized in that the chair back comprises a guide frame for one or more sections adjacent the seat, the upper sections being rigidly connected with at least one guide track which passes through the guides in the remaining sections.

In order to ensure equal spacing between the separate sections during adjustment, springs may suitably be arranged between each section.

Treatment chairs have previously been constructed with a minimum seat height of 50 cm. For various reasons it should be possible to lower the chair considerably more, even almost to the floor.

In this connection it is necessary to take into consideration that the distance between the operational area and the eyes of the operator should correspond to the usual reading distance. The construction of the chair, the actual operating positions and the position of the patient are all factors which are mutually concerned.

It is also necessary to take into consideration the fact that the dentist must be able to work as directly as possible.

Before the various operating positions are mentioned, the position of the patients body isfirst discussed. With the socalled washed field technique, the dentist works in sitting position and the patient is in almost horizontal position, i.e., sharply rearwardly inclined.

Treatment in such a rearwardly inclined position is limited in regard to the patient, in regard to the dentist and in regard to the previously known chair constructions. In many cases this method of treatment is not desirable since it can entail actual disadvantages in some cases. Treatment in an uprightly positioned lower jaw, for instance, is unnatural and can be better carried out in another manner.

In the following, the method of operating in a sitting position is further described. The working position of the dentist relative to the patient is divided according to a clock face, and at the 12 o'clock position the dentist is directly behind the patients head. Conventional working positions are 7, 8 and 9 o'- clock. However, it should also be possible to work at 10, ll, 12 and l oclock positions. These positions are difficult to assume with known treatment chairs. In order to work well in these positions it is necessary, particularly with bigger and more obese patients, that the patients head may be positioned in the lap of the dentist. This is only possible when the chair back fits the patient anatomically. In order to achieve the frequently desirable upright position of the patients head, in this position, it must be possible to lower the patient farther than was possible previously.

It is also desirable to dispense with the table type of construction, and to use the conventional and well-known type of head support. It is possible then at ll and 1 oclock positions to have access to the throat angle between head and shoulder. The sitting position of the dentist is then upright and comfortable. The ll oclock position, for instance, allows an extremely good and direct working position for all operations in the lower jaw and in the front of the upper jaw, and in part, the premolar area of the upper jaw. The 1 oclock position is advantageous with lingually positioned teeth in the right-hand part of the lower jaw. When operating in the rear areas of the upper jaw, all working positions can be considered. The working position used will vary from case to case and from dentist to dentist.

If the standing position of working is preferred no further requirements are necessary insofar as it is possible to raise the chair to sufiicient height.

The invention also relates to a head support for treatment chairs particularly for the type described hereinabove, and, according to the invention a head support is provided the guide member of which cooperates with he guide member of the chair back and is formed as one or more parallel rod elements, the characterizing feature of the head support according to the invention being that the rod element is divided into a plurality of pivotally connected links, the respective articulations being so formed that the links are adapted to pivot to one and the same side only. An articulated rod being thereby provided which is eminently suitable as guide member for a conventional, known head support plate. The separate links are provided with laterally projecting adjustment members which are actuated by an angle adjusting member. The angle adjusting member may be adapted for manual operation, e.g., a screw or eccentric device, but a hydraulic ram is preferably used, the piston rod of which actuates the adjustment members. The links are caused to be slow of movement, and reinforcing springs may be arranged between the separate links.

The invention is further described in the following with reference to the drawings which show a preferred embodiment of the invention.

All the drawings are in diagram from and illustrate only those parts of the chair which are necessary to the understanding of the invention.

FIG. 1 shows a side view of a chair according to the invention.

FIG. 2 shows the chair in FIG. 1 in the same view but with extended back.

FIG. 3 shows a plan view of the chair back in FIG. 1 and 2 with the chair back in the extended position shown in FIG. 2.

FIGS. 4 and 5 show a plan view and a side view respectively of three links which form an articulated rod element for the head support of the chair.

FIG. 6 shows a detail of the head support in particular a detail of the adjustment of the angle position of the articulated rod element.

In FIG. 1 the base of the chair is designated by 1. The footrest is not shown. The chair seat 3 is mounted in the base 1. The chair back 9 is rotatably mounted at 8 on the chair seat 3. The chair back 9 consists mainly of a frame 10 (see also FIG. 3) with guide grooves 11 and 12 for the back sections 13,14,15, 16 and 17. The portion of the chair back which forms the actual support for the patient is thus divided into a rigid element 18, which is rigidly connected with the back frame 10, and into five relatively displaceable sections 13-17. In the shown embodiment, the three lowest sections 13-15 are provided with adjustment members, so that the sections have guiding in the guide grooves 11 and 12. The top section 17 is provided with two guide rods 19 and 20 which are rigidly connected with the section 17 and extend through free bores in the sections 1316 and the section/frame 18/10. The bores in the rigid portion of the chair back are designated by 21, and 22 respectively. To ensure equal relative displacement helical springs 23 are arranged in the shown embodiment, between the separate sections as shown in FIG. 3. Receiving chambers 24 and 25 respectively are provided in the separate sections for receiving the springs when the sections are in intimate relationship In the shown construction the helical springs are threaded onto guide rods 19,20, the springs may, of course, be arranged in another manner, and any suitable type of spring means may also be used. In order to achieve the desired equidistant spacing other means may also be used, for instance a lazy-tongs.

As it will be apparent from FIGS. 1 and 3 the upper section 17 is connected to the piston rod 26 of a hydraulic ram 27 which in turn is connected with the frame 10. When the ram 27 is activated, the piston rod 26 is displaced in upward direction as indicated in FIG. 2, and the sections 13-17 are relatively displaced. The springs (shown only in FIG. 3) ensure an equidistant spacing of the section. In FIG. 2 the chair back is extended.

The head support 28 has a special construction with regard to the cooperating guide part of the chair back. The guide part is formed as an articulated rod element, i.e., a rod element which is divided into a plurality of links, the respective pivotal connections being so formed that the links may be pivoted to one and the same side only. FIGS. 4, 5 and 6 illustrate this further in the form of an embodiment example. In FIGS. 1 and 2 the rod element is designated by 29 and has, as indicated, guiding in the back in a guiding element 30. This guiding element 30 is also to be found in FIG. 6, which shows a section through the upper portion of the back section 17in the area at the rod element of the guide rod for the head support. The rod element 29 consists ofa plurality oflinks 31, 32, 33 34 and 35.

The manner in which the actual rod element is constructed is further illustrated in FIGS. 4 and 5 which show the connection and form of three consecutive links 32, 33 and 34. The links are identical and only the link 32 is further explained herein. The link 32 consists of a rod-formed part 36 of square cross-sectional configuration. A bolt 37 is inserted through the fore end thereof. Approximately in the center thereof the square rod 36 merges into a U-shaped channel cross-sectional configuration, with internal width sufficient to receive the square portion 38 of the adjacent element 33. The said square portion 38 corresponds to the square portion 36 on the link 32 and is pivotally connected with the link 32 by means of a bolt 39 which is passed into corresponding apertures in the two sidewalls of the channel. The said bolt 39 corresponds to the bolt 37. By means of this embodiment the separate links may be pivoted in one direction only, viz, as shown in FIG. 6. Each link, for example, the link 32, is provided with two projecting adjustment members 40 and 41. In the same way, the link 33 had two adjustment members 42 and 43. Between the links in this embodiment a spring 47 is tensioned, the one end of which is secured to the link 32, the spring being passed through a bore in the link 33 and secured thereto with its other end.

At the rear part of the back element 17, an angle-adjusting member 44 is arranged, in this case in the form of a small hydraulic ram with a piston rod 45. The piston rod 45 is connected to a fork 46 which forks over the square portion 38 on the link 34 and is adapted for engagement with the respective adjustment members, in this case adjustment members 42 and 43. On adjusting the head support, the rod element 29 is drawn out to the desired length in such a way that the link adjacent the guide 30 may be pivoted freely under the action of the ram 44, as shown in FIG. 6. When the ram 44 is activated, the fork portion 46 is pressed downwardly and into engagement with the adjustment members 42, 43, whereby the link 33 and thereby also the links 31, 32 beyond, etc., are pivoted upwardly to the position shown in FIG. 6, which is also clear from FIGS. 1 and 2. The rod element is locked in manner known per se in the guide 30 in more or less extended position and the desired angle position is adjusted by means of the ram 44, the fork portion 46 pressing against the adjustment members 42, 43. The adjustment members are of such length that the length of extension may be varied while retaining the cooperation between the fork portion 46 and the adjustment members 42, 43.

By means of the novel treatment chair in accordance with the invention, a chair is provided which allows anatomical fit to any patient, so that it is only the anatomy of the actual patient and not the chair which obstructs the dentist from access to the actual operational area, the oral cavity, both in standing and sitting working positions.

The invention is not restricted to the shown diagrammatical construction. For example, to regulate the back sections, it is also possible to use means other than a hydraulic ram, and the hydraulic ram may, e.g., be arranged within the back sections. By way of example it may be mentioned that bellows may also be used between the back sections so that the back forms a whole seat from the outside, and the separate back sections may also be effected in mutual overlapping relationship, so that a whole back surface is achieved. The guiding of the separate sections may also be effected in other suitable ways.

Having described my invention, I claim:

1. A treatment chair having a seat, a backrest and a head support, means to adjust the length of the backrest, the backrest being divided into a plurality of sections, means mounting said sections for movement toward and away from each other, spring means acting between said sections to space said sections equal distances apart regardless of the adjusted length of the backrest, a rod mounting said head support on the section of the backrest that is farthest from said seat, said rod being slidable relative to the last-named section to adjust the distance of said head support from said last-named section, said rod being divided into a plurality of pivotally connected links which pivot relative to each other in only one direction.

2. A treatment chair as claimed in claim 1, said links having laterally projecting adjustment members, and angle-adjusting means for adjusting said adjustment members. 

1. A treatment chair having a seat, a backrest and a head support, means to adjust the length of the backrest, the backrest being divided into a plurality of sections, means mounting said sections for movement toward and away from each other, spring means acting between said sections to space said sections equal distances apart regardless of the adjusted length of the backrest, a rod mounting said head support on the section of the backrest that is farthest from said seat, said rod being slidable relative to the last-named section to adjust the distance of said head support from said last-named section, said rod being divided into a plurality of pivotally connected links which pivot relative to each other in only one direction.
 2. A treatment chair as claimed in claim 1, said links having laterally projecting adjustment members, and angle-adjusting means for adjusting said adjustment members. 